Seamless and Seeded Isosurfaces
(Summer Work Report)

Gunther Weber
Oliver Kreylos

UC Davis

Monday, September 18, 2000
1:00 - 2:00 PM
50F Conference Room

Currently the Visualization Group works with researchers who are doing
adaptive mesh refinement, AMR, computations and/or generating large data
sets. Gunther and Oliver have each been working on one aspect of the
visualization problems which arise.

Gunther has been working on generating an isosurface directly from scalar
AMR data. Since there is overlapping data and data at different resolutions,
most straightforward extensions to existing isosurface algorithms
lead to overlaps and/or cracks. The goal of this work was to find a more
general technique which is still efficient but which doesn't contain
artifacts.

Gunther will be presenting a method for "stitching" the AMR grids together
in such a way that a seamless isosurface can be generated efficiently.
This is done by using fast, existing algorithms everywhere but at the
boundaries between different resolution grids. At the boundaries, the
data is "stitched" together to form "cells" for which isosurfaces can be
efficiently generated. This "stitching" can be applied to a much more
general class of overlapping grids and it can be used as the basis for
extensions of other visualization algorithms.

Oliver has been working on generating interactive isosurfaces for the
exploration of large data sets in an immersive (VR) environment.
A lot of scientific research these days is performed by gathering and
analyzing hideous amounts of data. No matter if this data is the result
of real-world measurements or of numerical simulations, extracting
information from it becomes more and more difficult as the amount of
data grows. Thus, scientific visualization is becoming a major tool of
research: The human visual system is unparalleled in its capacity to see
patterns or detect features in vast amounts of data.

The effectiveness of scientific visualization can be further enhanced by
employing virtual-reality methods: The combination of true 3D
(stereographic) output, 3D input devices and interactivity enables a
user to explore an unknown 3D data set with unprecedented ease.

Oliver's talk will concentrate on a data exploration system he implemented as
a summer project with the Visualization Group. This tool allows a
user to expand an isosurface from an arbitrary point inside a data set,
and to animate sets of isosurfaces by moving the point of interest.